Which of the following numbers is a factor of 48? ${3,7,9,13,14}$
By definition, a factor of a number will divide evenly into that number. We can start by dividing $48$ by each of our answer choices. $48 \div 3 = 16$ $48 \div 7 = 6\text{ R }6$ $48 \div 9 = 5\text{ R }3$ $48 \div 13 = 3\text{ R }9$ $48 \div 14 = 3\text{ R }6$ The only answer choice that divides into $48$ with no remainder is $3$ $ 16$ $3$ $48$ We can check our answer by looking at the prime factorization of both numbers. Notice that the prime factors of $3$ are contained within the prime factors of $48$ $48 = 2\times2\times2\times2\times3 3 = 3$ Therefore the only factor of $48$ out of our choices is $3$. We can say that $48$ is divisible by $3$.